"Europa is the most likely place in our solar system beyond Earth to possess .... life," said Robert Pappalardo, a planetary scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

"And it is the place we should be exploring now that we have a concept mission we think is the right one to get there for an affordable cost," he continued.

"Europa is the most promising in terms of habitability because of its relatively thin ice shelf and an ocean ... And we know there are oxidants on the surface of Europa."

At the request of NASA, a proposed mission to explore Europa was revised to significantly reduce the cost, the scientist told the media on the sidelines of an annual conference of the American Association for the Advancement of Science (AAAS) underway here.